1. Field of the Invention
The invention relates to a fuel cell module and a fuel cell motor vehicle equipped with the fuel cell module. More particularly, the invention relates to a technology for ensuring safety at the time of maintenance of the vehicle or the like by shutting off the output of electric current from the fuel cell module.
2. Description of the Related Art
In recent years, motor vehicles employing fuel cells as a drive energy source have drawn attention, and have been produced as prototypes as an approach to solving environmental issues. An example of such motor vehicles is a fuel cell motor vehicle in which a fuel cell is installed at a site near a center of the vehicle, such as a space below a seat, taking into consideration the weight balance of the vehicle, the installation space, etc. Lately, installation of a fuel cell in a forward portion of a vehicle is considered. The development of fuel cell motor vehicles is now at a stage where near-future widespread commercialization is aimed and expected.
A fuel cell capable of driving a vehicle produces relatively high voltage. Therefore, during maintenance of the vehicle or the like, output of voltage from the fuel cell module, if any, is undesired in terms of safety. Furthermore, since cooling water is circulated between the fuel cell module and a radiator, and is delivered into the interior of the fuel cell, an intermediate electric potential between the potential of the positive electrode and the potential of the negative electrode of the fuel cell may occur in the cooling water. That is, due to the cooling water, the intermediate electric potential is extracted out of the fuel cell module. That is, the fuel cell has a characteristic that high voltage can occur between the cooling water and the positive electrode, and between the cooling water and the negative electrode. This characteristic of the fuel cells is not considered in the conventional safety measures against electricity leakage and the like. There is another problem of an insufficient safety measure against electricity leakage and the like in the case of breakage of a fuel cell module caused at the time of a collision of the vehicle with an object.